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1 Introduction

A wide variety of contaminants are to be found in our environment – in soil, sediments, water and air. As a result we need to be able to tell when these contaminants are at concentrations that may be harmful. Numerical values that represent concentrations of contaminants in these environmental media that are protective of the environment and/or human health are used in many countries, including New Zealand. In this document these values are referred to as environmental guideline values.

If, as a result of site contamination, concentrations exceed these guideline values, a variety of actions may occur, including:

  • further site investigation
  • site remediation or management.

Guideline values are generally established in guideline documents or as environmental standards prepared by national jurisdictions (eg, Ministry for the Environment, 2011, 1997; 1999) or overseas agencies (eg, CCME, 2002; ANZECC and ARMCANZ, 2000). Many of these documents are used in New Zealand for assessing contaminated land. The guideline values contained in these documents may be referred to as environmental quality guidelines, trigger levels, intervention levels, maximum acceptable values, remediation goals, screening levels or acceptance criteria, and have been derived for different management purposes or as the result of directed research (Cavanagh and O’Halloran, 2002).  The guideline values may relate to different receptors and have been calculated using different methodologies and assumptions (Cavanagh and O’Halloran, 2003).

Given these differences in derivation and purpose it can be confusing knowing which guideline value to choose for a given assessment scenario, or how the value should be applied to the investigation or management of a contaminated site.

Because of their responsibilities under the Resource Management Act 1991, regional councils and territorial local authorities are regularly contacted by environmental consultants and other interested parties for guidance on the use of appropriate guideline values. This advice can include which guideline values are acceptable for assessing or managing contaminated sites, and, where more than one set of values is available, in what order of preference they should be used.

Now, however, there is  a national Methodology for Deriving Standards for Contaminants in Soil to Protect Human Health (the Methodology – Ministry for the Environment, 2011). The Methodology supports the National Environmental Standard (NES) for Assessing and Managing Contaminants in Soil to Protect Human Health. The scope and application of the NES means that Guideline No. 2 and the associated EGV database should be used only in instances where there is no appropriate soil contaminant standard – and the assessor chooses not to derive a value using the Methodology – or when the NES does not apply.

This guideline document will assist risk assessors to select and apply environmental guideline values (complementary to the NES) when assessing contaminated land and reviewing site investigation reports.  Previous guidance has been provided on the information requirements to be provided by consultants (and their clients) in site investigation reports (Ministry for the Environment, 2001).

This document outlines the reference documents containing guideline values, including those most commonly used by contaminated site practitioners in New Zealand, and provides background information on the guideline values contained in each reference document, and guidance on selecting the appropriate guideline values.

The Environmental Guideline Value (EGV) database has been developed as a companion to this guideline document.  The EGV database contains the guideline values provided in the reference documents discussed in this document.  The database maintains the hierarchy established in this document and is intended to provide a rapid and user-friendly reference to the guideline values. However, users are cautioned against using the EGV database simply as a series of look-up tables: it is important to be fully conversant with the derivation of guideline values used in site investigation reports.

Neither the guideline document nor the EGV database is intended to replace the original reference documents.  Users of both are strongly advised to refer to these reference documents for the latest derivation and application of the guideline values, and to ensure that the values in the database have not been superseded.

The EGV database can be downloaded from the Ministry for the Environment’s website.

Changes from the 2003 version

This document has had minor updates including:

  • updated website URLs
  • updated references to other documents and government departments
  • references to the Resource Management (National Environmental Standard for Assessing and Managing Contaminants in Soil to Protect Human Health) Regulations (to take effect on 1 January 2012).